Process for the manufacture of alpha:beta-unsaturated carboxylic acid esters from beta-halogen carboxylic acid esters



UNITED sTArs PATENT OFFICE PROCESS FOR THE MANUFACTURE OF at fi-UNSATURATED CARBOXYLIC ACID ESTERS FROM {El-HALOGEN CARBOX- YLIC ACID ESTERS Daniel Porret, Monthey, Switzerland, assignor to Ciba Limited, Basel, Switzerland, a Swiss firm No Drawing. Application October 27, 1950, Serial No. 192,626

Claims priority, application Switzerland November 4, 1949 7 Claims. (01. 260-486) 1 i 2 It is known that one-unsaturated carboxylio droxide, sodium carbonate, potassium carbonate acid esters can be made from halogen-carboxylic and the like, can be used, and that the use of acid esters by splitting off hydrogen halide. Howsuch mixtures enables the amount of aliphatic ever, the splitting off of hydrogen halide, which tertiary amine to be reduced to about 20 per can be carried out by known methods, for ex- Cent. ample, by treating the halogen-carboxylic acid AS Starting materials for u in the present ester with an acid agent capable of splitting off process h r may b m n ion d, f r x mp hydrogen halide, such as concentrated sulfuric fipi id esters u h as he hyl, acid, phosphoric acid or zinc chloride, leads in s p yl r uty st and a fi-p y -fimost cases to unsatisfactory yields owing to the chlom-prepionic d st rs, fi-fu yl-fi-chlorooccurrence of side reactions. Furthermore, the Dropionie acid esters, fi-eh10l0buty1rie a d eS- use of inorganic bases such, for example, as soters and fiy d esters. The

dium carbonate, potassium hydroxide or alcocorresponding m n mpound m y, of holic solutions of alkali hydroxides, is attended course, e150 be u d, Whe eas the iodine c0 by various disadvantages, especially in view of pounds a p to e p ct cally unsuitable.

this reason it has been proposed to use aromatic butylamine trioetylemine- E p y Suittertiary amines such as dimethylaniline or diable, however, are the lower ert ary amines conethsdaniline However, the plitting 01f f taim'ng 3-9 carbon atoms such as trimethylamine, drogen halide from halogen-carboxylic acid estriethylamine or i opy amine.

ters by means of these amines takes place with The production of aifi-unsetureted cal'boxylie sumcjeni; speed only t relatively high temperaacid esters in accordance with the present inventures; and side reactions cannot be avoided, non may be conducted 1n the p e nce 01 absince, for example, the amines used are partial sence of Water an Organic o vent The re- 1y decomposed by t hydrogen hahde f rmed so action temperature may vary within fairly wide th t m addltlon t a leduced yleld of the a limits depending on the starting materials used unsaturated carboxylm acid esters there is also on the Teactlvlty the fl y p atle a l of aromatic amine amine Preferably, however, the temperature The present invention is based on the uneX should neither substantially exceed 100 C nor pected Observation t mfimnsatumted cap substantially fall below 70 0.; it is of advantage boxylic acid esters such as acrylic acid esters, to Work at In the case of are-unsaturated reaction prodcinnamic acid esters, methacrylic acid esters and ucts Whlch polymfarize easily it is of advantage th correspondmg -halmen calboxyhc acld of a polymerizat on inhibitor such for example, ters by treating the halogen-carboxylic acid esas hydroqumPneters with tertiary aliphatic amines. The split- The followmg examples illustrate th inve ting oiT of hydrogen halide by means of these On, the parts being by weight unless otherwise amines takes place unexpectedly almost quam stated and the relationship of parts by weight titatively even at temperatures sufficiently low to enable side reactions to be avoided. In this way kflogmm to the liter:

it is possible, not only to obtain very high yields Exa l 1 of cup-unsaturated carboxyhc acid esters, but

phatic tertiary amine used for the splittins 01f 0 parts by volume of water and 0.2 part of hydroof hydrogen halide. It has also been observed quinone are heated for 1 hours in a reflux a instead of using the aliphatic tertiary .50 apparatus at about C.,wh1le stirring. A preacrylic acid ester formed is distilled in the form of an azeotropic mixture with water at 40 C. and under a pressure of about 80 mm. The aqueous layer is separated, and 102 parts of acrylic acid ethyl ester containing 2-3 parts of water are obtained. The yield is almost quantitative. By adding caustic soda solution to the distillation residue 112 parts of triethylamine having a purity of 85 per cent are obtained, which may be used directly for a subsequent reaction. The remainder of the triethylamine (7 parts) can be recovered by distillation.

Instead of triethylamine a corresponding quantity of tripropylamine may be used.

Example 2 A mixture of 150.5 parts of B-chloro-propionic acid iso-propyl ester, 105 parts of triethylamine, parts by volume of water and 0.2 part of hydroquinone is heated for 1 hours in a reflux apparatus at about 80 C. 150 parts by volume of water are added to the reaction mixture and the excess of amine is neutralized. The acrylic acid ester formed is then distilled with steam under a pressure of about 80 mm. After separating the aqueous layer, there are obtained 109 parts of acrylic acid isopropyl ester containing traces of water. The yield amounts to 95 per cent of the theoretical yield.

Instead of triethylamine there may be used a corresponding quantity of tributylamine.

Example 3 A mixture consisting of 164.5 parts of d-chloropropionic acid butyl ester, 105 parts of triethylamine, parts by volume of water and 0.2 part of hydroquinone are heated for 1% hours in a reflux apparatus at about 90 C. When the reaction has finished 150 parts by volume of water are added, and then the mixture is acidified. By distilling at C. under "10 mm. pressure. there is obtained a mixture of acrylic acid butyl ester and water. After separating the water, 125 parts of acrylic acid butyl ester are obtained. The yield amounts to 98 per cent of the theoretical yield.

Example 4 A mixture of 276.5 parts of the ester of ,8- chloropropionic acid with 2:6:8-trimethyl-nonyl- 4-01, 105 parts of triethylamine, 20 parts by volume of water and 0.2 part of hydroquinone is heated for 1 hours in a reflux apparatus at about 90 C. When the reaction has finished, 200 parts by volume of water are added to the mixture and the whole is then acidified. The acrylic acid ester so obtained is separated from the aqueous layer and purified by distillation at 80 C. under a pressure of 0.3 mm. of the purified acrylic acid ester is obtained.

Example 5 A mixture of 190.5 parts of B-chloropropionic acid cyclohexyl ester, 105 parts of triethylamine,

20 parts by volume of water and 0.2 part of hydroquinone is heated for 1 hours in a reflux apparatus at about 90 C. The mixture is then cooled and mixed with 200 parts by volume of water. The resulting acrylic acid ester is isolated and purified by distillation at 60 C. under 0.3 mm. pressure. In this manner the pure acrylic acid cyclohexyl ester is obtained in good yield.

Example 6 A mixture of 136.5 parts of fl-chloropropionic acid ethyl ester, 25 parts of triethylamine, 110

parts of sodium hydroxide solution of 30 per cent strength and 0.2 part of hydroquinone is heated for 1% hours in a reflux apparatus at about C. 150 parts by volume of water are added to the reaction mixture and the excess of amine is neutralized. The acrylic acid ester so obtained is then distilled with steam under a pressure of about 80 mm. After separating the aqueous layer there are obtained 102-103 parts of acrylic acid ethyl ester containing 2-3 parts of water. The yield is approximately quantitative. By rendering the residue alkaline and distilling with steam, the amine is recovered almost quantitatively in the form of a solution of about 80 per cent strength.

Example 7 A mixture of 178.5 parts of 5-0111010-01-11181311371- propionic acid butyl ester, 105 parts of triethylamine, 25 parts by volume of water and 0.2 part of hydroquinone are heated for one hour in a reflux apparatus at 80-90" C., while stirring. Upon cooling, a precipitate of triethylamine hydrochloride separates out. 200 parts by volume of water are added in order to dissolve the hydrochloride, the excess of amine is neutralized by the addition of dilute sulfuric acid and then the resultant methacrylic acid butyl ester is distilled oif in good yield in the form of an azeotropic mixture with water. After separating the aqueous layer, the methacrylic acid butyl ester formed is isolated. In order to prevent any polymerization, the distillation is advantageously carried out in the presence of metallic copper.

What I claim is:

1. A process for the manufacture of an afi-llnsaturated. carboxylic acid ester from the corresponding saturated d-halogen carboxylic acid ester, the halogen atom of which is a member selected from the group consisting of chlorine and bromine, and the u-carbon atom of which is free from any halogen atom, comprising splitting off hydrogen halide by treating the B-halogen carboxylic acid ester with an aliphatic tertiary amine and an inorganic base.

2. A process for the manufacture of an ocfi-UB- saturated carboxylic acid ester from the corresponding saturated p-halogen carboxylic acid ester, the halogen atom of which is a member selected from the group consisting of chlorine and bromine, and the a-carbon atom of which is free from any halogen atom, comprising splitting ofi hydrogen halide by treating the fl-halogen carboxylic acid ester with an aliphatic tertiary amine containing 3-9 carbon atoms and an inorganic base.

3. A process for the manufacture of an afi-unsaturated carboxylic acid ester from the corresponding saturated fl-halogen carboxylic acid ester, the halogen atom of which is a member selected from the group consisting of chlorine and bromine, and the a-carbon atom of which is free from any halogen atom, comprising splitting off hydrogen halide by treating the B-halogen carboxylic acid ester with an aliphatic tertiary amine containing 3-9 carbon atoms and an inorganic base selected from the group consisting of an alkali metal hydroxide and of an alkaline earth metal hydroxide at '70-100 C.

4. A process for the manufacture of an a,fl-llnsaturated carboxylic acid ester from the corresponding saturated p-halogen carboxylic acid ester, the halogen atom of which is a member selected from the group consisting of chlorine and bromine, and the a-carbon atom of which is free from any halogen atom, comprising splitting ofi hydrogen halide by treating the p-halogen carboxylic acid ester with triethyl amine and sodium hydroxide at 70-100 C., the triethyl amine constituting at least 20 per cent. of the total weight of the triethyl amine and the sodium hydroxide.

5. A process for the manufacture of an O S-unsaturated carboxylic acid ester from the corresponding saturated B-chloro-carboxylic acid ester, the a-carbon atom of which is free from any halogen atom, comprising splitting off hydrogen chloride by treating a p-chloro-carboxylic acid ester with an aliphatic tertiary amine containing 3-9 carbon atoms and an inorganic base of the group consisting of an alkali hydroxide and an alkaline earth metal hydroxide at 70-100 C.

6. A process for the manufacture of an c p-unsaturated carboxylic acid ester from the corresponding saturated fi-chloro-carboxylic acid ester, the a-carbon atom of which is free from any halogen atom, comprising splitting off hy- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,864,884 Bauer June 28, 1932 2,298,739 Lichty Oct. 13, 194 2 2,326,095 DIanni Aug. 3, 1943 2,376,067 Long May 15, 1945 2,386,694 Lichty Oct. 9, 1945 

1. A PROCESS FOR THE MANUFACTURE OF AN A, B-UNSATURATED CARBOXYLIC ACID ESTER FROM THE CORRESPONDING SATURATED B-HALOGEN CARBOXYLIC ACID ESTER, THE HALOGEN ATOM OF WHICH IS A MEMBER SELECTED FROM THE GROUP CONSISTING OF CHLORINE AND BROMINE, AND THE A-CARBON ATOM OF WHICH IS FREE FROM ANY HALOGEN ATOM, COMPRISING SPLITING OFF HALOGEN HALIDE BY TREATING THE B-HALOGEN CARBOXYLIC ACID ESTER WITH AN ALIPHATIC TERTIARY AMINE AND AN INORGANIC BASE. 